State `._pth` files are Windows-only

[htgoebel]

Documentation

The section about ._pth files (these with the underscore) does not state that this feature is Windows-only. The section says: "The shared library path is always known on Windows, however it may not be available on other platforms." But up to this sentence, there is no mention of shared library path — leaving the impression that ._pth files work on all plattforms, just shared library path might not.

OTOH the source https://github.com/python/cpython/blob/v3.14.0/Lib/test/test_site.py#L661 clearly states that ._pth files are Windows-only.

Expected

Either in the section head or at the very beginning of this section state "Windows only".